new to programming and to Daniweb

Hi, everyone. I'm exploring programming on my own using Runestone Interactive to learn some Python and also reading a bit of the Perl documentation that can be installed on Linux through the perl-doc package. I'm also thinking of checking out the w3schools tutorials for web development.

My first question is what people think of Runestone Interactive for someone who has no previous education or experience in programming. I am enjoying it but don't know whether there might not be a better approach I could take to getting my feet wet. (I wanted to try the 3rd edition of How to Think Like a Computer Scientist as edited by Peter Wentworth but it would require me to install Windows and I don't want to.

Another question is whether I should be learning Tk or something else if I want to do graphical user interfaces, which you pretty well have to if you're going to write any applications.

And another question is whether maybe I shouldn't just jump right into Java or C because those are much more common on Windows machines so that other people could actually run my applications.